One of the technical fields undergoing the most intensive development is the field of EGR system heat exchangers since the space and packaging requirements call for increasingly smaller and more efficient devices to allow discharging the same amount of heat in a smaller space.
When devices are smaller, the same temperature differences are found between areas located closer to one another and therefore result in higher temperature gradients.
Additionally, heat exchangers formed by a shell housing a bundle of exchange tubes where this bundle of tubes extends between two baffles have the drawback of differential expansion occurring between the shell, directly in contact with the coolant liquid, and in the bundle of tubes, also in direct contact with the hot gas to be cooled. Differential expansion between one component and another is particularly pronounced in the longitudinal direction established by the main direction along which the bundle of tubes extends.
Among the technical solutions known for preventing differential expansion between the shell and bundle of tubes from giving rise to stresses causing breaks are those based on floating core configurations. The core is the bundle of heat exchange tubes where the tubes are attached at least between two end baffles. One baffle is conjoint with the shell and the other baffle, i.e., the baffle corresponding to the floating end, allows relative movement with respect to the shell. The baffle that allows movement is usually connected, according to the particular configuration of the exchanger, by an elastically deformable element establishing the fluid continuity of the hot gas conduit and it is the one which allows thermal expansion.
Both fixed and movable baffles are walls located transverse to the bundle of tubes. If the hot gas inlet is at the floating end, the movable baffle is the one that is subjected to higher temperature. Given that the baffle is movable, the coolant liquid flow tends to flow around the perimetral area of the baffle. This condition leads to a stagnation point or region causing the coolant liquid to remain in the hot area without discharging heat until reaching the boiling temperature. This is one of the causes generating thermal fatigue and failure of the device.
The present disclosure proposes a particular configuration of a floating core device in which the existence of stagnation regions in the baffle on the floating side is prevented, preventing thermal fatigue and therefore prolonging the service life of the device.